1. Field of Invention
This invention relates to the beneficiation of oxidic ores, that is, to the removal of values of an undesired constituent, normally a metal, from an ore thereby substantially raising the residual content of another, desired, constituent, usually a metal, present in the ore. Such values will usually be present in the ore in the form of oxides. The invention also relates to the beneficiation of industrial oxidic waste materials on a similar basis.
According to one aspect thereof the present invention more particularly relates to beneficiation of an iron-containing oxidic ore by selectively chlorinating iron values in the ore and removing the resulting iron chloride from the ore residue in the form of a vapour.
2. Brief Description of the Prior Art
British Pat. No. 1359882 discloses a process for the benefication of an ore containing as major constituents titanium and iron oxides, which process comprises forming a mixture containing the ore and carbon, the carbon content of the mixture being in the range of from 20% to 40% by weight, and treating the mixture in a fluidised bed reactor at a temperature in the range of from 800.degree. C. to 1000.degree. C. with a treatment gas which comprises from 20% to 50% by volume of chlorine and from 0% to 10% by volume of oxygen. In order to reduce the quantity of chlorine required it is preferred to operate this process so that the predominant chlorination product is ferrous chloride.
The selective chlorination of the iron values in an ore also containing titanium values according to the process described in British Pat. No. 1359882 may be explained theoretically, on thermodynamic principles, to involve the initial chlorination of both the titanium and iron values of the ore with the preferential reoxidation of the titanium chloride so formed by the oxygen released in the course of the chlorination reaction.
Such a theory does not lend itself to the expectation that the benefication process similar to that described in British Pat. No. 1359882 could be applied to a wide range of oxidic ores containing, as major constituents, besides iron values, normally chlorinatable values of a wide range of metals other than titanium. In many cases vapour pressure considerations would lead to the expectation that the desired selective removal of iron values could not be achieved. Nevertheless, it has now been found, according to the present invention, that an excellent selectivity with respect to the removal of the iron values in the ore may be achieved, under the particular conditions used, over a wide range of ores as will be fully described hereafter. The wide ranging application of the present invention leads to the belief that a different mechanism, to that based on the thermodynamic principles mentioned above, is operable under the particular process conditions utilised in the practice of the present invention.